55 citations · 183 across the 12 of their papers we have counts for
12 papers
Review of point defect structures in hexagonal close packed metals and across the Periodic Table
Andrew Ralph Warwick, Pui-Wai Ma, Sergei Lvovich Dudarev
We present a comprehensive ab initio dataset of formation energies and elastic properties of intrinsic point defects across all the transition and rare earth hexagonal close packed…
Activation Functions for "A Feedforward Unitary Equivariant Neural Network"
Pui-Wai Ma
In our previous work [Ma and Chan (2023)], we presented a feedforward unitary equivariant neural network. We proposed three distinct activation functions tailored for this network:…
Negative Temperature in Spin Dynamics Simulations
Pui-Wai Ma, Sergei L. Dudarev
A simple and computationally efficient algorithm enables implementing negative temperature values in a spin dynamics simulation. The algorithm uses a Langevin spin dynamics thermos…
Simulations of Nanocrystalline Iron Formation under High Shear Strain
Ivan Tolkachev, Pui-Wai Ma, Daniel Mason +1
High-shear methods have long been used in experiments to refine grain structures in metals, yet the underlying mechanisms remain elusive. We demonstrate a refinement process using…
A Feedforward Unitary Equivariant Neural Network
Pui-Wai Ma, T. -H. Hubert Chan
We devise a new type of feedforward neural network. It is equivariant with respect to the unitary group . The input and output can be vectors in with arbitrary…
A Machine-Learned Spin-Lattice Potential for Dynamic Simulations of Defective Magnetic Iron
Jacob Bernard John Chapman, Pui-Wai Ma
A machine-learned spin-lattice interatomic potential (MSLP) for magnetic iron is developed and applied to mesoscopic scale defects. It is achieved by augmenting a spin-lattice Hami…
Effect of Non-Heisenberg Magnetic Interactions on Defects in Ferromagnetic Iron
Jacob B. J. Chapman, Pui-Wai Ma, Sergei L. Dudarev
Fundamental flaws in the Heisenberg Hamiltonian are highlighted in the context of its application to BCC Fe, including the particular issues arising when modelling lattice defects.…
The Dynamics of Magnetism in Fe-Cr Alloys with Cr Clustering
J. B. J. Chapman, S. L. Dudarev, P. -W. Ma
The dynamics of magnetic moments in iron-chromium alloys with different levels of Cr clustering show unusual features resulting from the fact that even in a perfect body-centred cu…
Dynamic Simulation of Structural Phase Transitions in Magnetic Iron
Pui-Wai Ma, S. L. Dudarev, Jan S. Wróbel
The occurrence of bcc-fcc (-) and fcc-bcc (-) phase transitions in magnetic iron stems from the interplay between magnetic excitations and lattice vibrations. However,…
Hubbard-like Hamiltonians for interacting electrons in s, p and d orbitals
M. E. A. Coury, S. L. Dudarev, W. M. C. Foulkes +3
Hubbard-like Hamiltonians are widely used to describe on-site Coulomb interactions in magnetic and strongly-correlated solids, but there is much confusion in the literature about t…
Constrained non-collinear magnetism in disordered Fe and Fe-Cr alloys
D. Nguyen-Manh, Pui-Wai Ma, M. Yu. Lavrentiev +1
The development of quantitative models for radiation damage effects in iron, iron alloys and steels, particularly for the high temperature properties of the alloys, requires unders…
Interatomic exchange coupling of BCC iron
Hai Wang, Pui-Wai Ma, C. H. Woo
We performed first-principle calculations on the exchange interaction (EI) between atoms in BCC-Fe strained volumetrically. Our results show that the volume-dependence of the EI de…